Heat exchanger



Jan. 18, 1966 w. PlLNlK ETAL 3,229,758

HEAT EXCHANGER Filed March 18, 1965 United States Patent 3,229,758 HEAT EXCHANGER Walter Pilnik, Zurich, and Werner Wieser, Kreuzlingen, Thurgau, Switzerland, assgnors to Ohipektn A.G., Bischofszell, Switzerland Filed Mar. 18, 1963, Ser. No. 265,638 Claims priority, application Switzerland, Mar. 20, 1962, 3,314/ 62 6 Claims. (Cl. 165-90) 'I'he present invention relates to a heat exchanger, for example to a cooling apparatus for concentrated fruit juice or other viscous fluids in the foods industry.

As is well known, every treatment of such goods requires that no undesired change is produced in the goods themselves. It is important for such a careful treatment that the whole quantity of goods be processed in an absolutely uniform manner and during as short a time as possible. This also applies to heat treatments such as heating and cooling.

Therefore, heat exchangers to be used for effecting such treatments must ensure perfect transmission of heat even over long periods of continuous operation, and uniform action on the whole stream of goods circulated through the heat exchanger.

It is a main object of the present invention to provide a heat exchanger fulfilling these requirements.

It is another and more specific object of the invention to provide a comparatively wide circulating space, which is narrowed in one place only, for the circulation of the lluid to be treated by heat exchange. The object aimed at by such provision is to ensure that even though the fluid is circulated at a moderate speed only, a high local speed thereof, and accordingly improved heat transfer will be obtained at its passage through the said narrowed place, and that even though a comparatively large overall crosssection is available for the circulation of the fluid to be treated, this will be -subjected -to the heat-supplying or heat-removing action in the form of a stream of comparatively small thickness at the narrowest place of its path, where heat exchange is most effective.

A further object of the invention is to provide a heat exchanger in which the fluid is constantly stirred and mixed within the heat exchanger in order to prevent retention of the fluid at the heat exchange surfaces, which would impair the heat transfer especially from and into the core of the stream Lof the fluid, and in order to ensure uniform treatment of the whole quantity of such fluid.

Further objects and advantages of the invention will appear from the description, now to follow, of an embodiment of the invention shown by way of example only in the accompanying drawing.

This drawing represents a heat exchanger in vertical section through the axis of its casing.

1 designates a table-like supporting frame on the top plate 1a of which the bottom 2a of a cylindrical, doublewalled casing 2 is fixed. A downwardly extending cylindrical projection 2b of the casing bottom 2a is lined with a bearing sleeve 3a made from synthetic material, which serves as a radial bearing to the lower portion 4a of an eccentric shaft 4a, 4b. This shaft 4a, 4b has a collar portion 6 which rests on top of the bearing sleeve 3a with the interposition `of an intermediate ring 5. A bearing ring 7 made from synthetic material to seated on the casing bottom 2a around the collar 6 and provides axial support for the bottom 8a of a cylindrical drum 8. An upwardly extending cylindrical recess 8b in the drum bottom 8a rotatably fits an another bearing sleeve 3b which is fixed to the upper portion 4b of the eccentric shaft, whereby that recess 8b is coaxial with the eccentric shaft portion 4b. The eccentricity between the axis a of shaft portion 4a and the axis b of shaft portion 4b "ice is comparatively small and in practice may amount, for example, to less than 0.2 inch where the inner diameter of the casing is about 22 inches. Also, the difference between the inner diameter of the casing and the outer diameter of the drum is comparatively small; for example, with an inner diameter of the casing of about 22 inches, the outer diameter of the drum may be about 21.6 inches. At any rate, the dimensions should' be chosen so that the radial width c `of the interval between the wall `of the casing 2c and that of the drum S at the widest place of the heat exchange space formed by that interval is, for example, between 5 and 20 times the width d of that same interval -at the narrowest place of the heat exchange space.

In the double-walled peripheral wall portion 2c of the casing 2 which surrounds the drum S, a helical duct 9 is formed by a helical separation 2d extending between the two walls. This duct has an inlet 10 at the top and an outlet 11 at the bottom. In a similar way, a helical duct 12 is formed by a helical separation 8d between the two walls of the double-walled peripheral portion 8c of the drum 8. An inlet tube 13 is connected from the inside -of the drum, near the bottom thereof, to the lower end of the helical duct 12, and an outlet tube 14 is similarly connected to that duct 12 in the uppermost part of the drum. The tubes 13 and 14 are continued upwards at 13b and 14b, respectively, in coaxial arrangement with each other and with the axis b, and there are corresponding inlet and outlet connections 13a and 14a, respectively in a connection body 15 surmounting the apparatus.

A hollow eccentric driving shaft l16 through which the tubes 13 and 14 are carried upwards from the drum 8 to the connection body 15 is sup-ported coaxially with the casing axis a in the cover 2e of the housing 2 by means of a bearing 27. Above that cover, the driving shaft 16 carries a driving sprocket wheel 17 which is in driving connection, by means of a chain 18 which runs over a tensioning sprocket 19, with a driving sprocket 2) keyed to the shaft of an electric motor 21 mounted on the upper part of the casing 2. The eccentric driving shaft 16 is also rotatably supported, on one hand, on the connection body 15, and on the other hand, in an extension 22 on top of the drum 2, in alignment with the axis b of the latter.

The interval created between the casing bottom 2a and the drum bottom 8a by the bearing ring 7 acting as a spacing member has an inlet 23 for the medium to be subjected to heat exchange and it moreover communicates with the heat exchange space itself formed by the interval between 4the peripheral walls 8c of the drum and 2c of the casing. The upper edge of the inner wall of the double-walled peripheral portion 2c of the housing serves as an overflow edge for the treated medium, an outlet 24 being provided in the outer wall lof the casing which is continued upwardly beyond the region of the said overflow edge. An overflow collector groove 25 from which the outlet 24 starts is formed between the outer peripheral wall and the overflow edge of the inner peripheral wall, by an upper closure wall of the helical duct in the double-walled peripheral portion 2c of the casing.

The described heat exchanger is particularly suitable for the cooling of concentrates in the processed .fruit food industry. The cooling medium, e.g. water, is continuously carried both through the helical duct 9 in the casing 2 and through the helical duct 12 in the drum 8. The concentrate itself is supplied under pressure through the inlet 23 to the space between ythe bottoms 2a and 8a. While the motor 21 runs, the eccentric driving shaft 16 is driven by means of the chain 18 which runs over the sprocket wheels 20, 19 and 17, so that it rotates about the axis a. The radial ribs 26- provided on the underside of the drum bottom 8a then act as propelling vanes to displace the concentrate continuously outwards into the cooling space of crescent-shaped crosssection. While the drum is caused to travel along a circular path, this 4cooling space continuously moves about the axis rz along the periphery of the casing, whereby the concentr-ate is squeezed at high speed through the narrowest portion of the interval between the casing and the drum and thereby is continuously stirred, mixed and circulated. Thus, no layers of concentrate can adhere to the walls of the drum or casing and no badly cooled core can develop within the stream of concentrate. The cooled concentrate eventually proceeds over the overow edge of the casing wall into the collecting groove 25 and leaves the apparatus through the outlet 24.

It will be understood that the described heat exchanger can also be used for heating a fluid medium, in which case a heating medium rather than a coolant is circulated through the helical ducts 9 and 12 of the casing .and drum walls respectively. It would also be possible without departing from the invention to supply either the peripheral wall of the casing only, or that of the drum only, with a cooling or heating medium.

It has been found that the best results, especially with casing diameters exceeding inches are obtained, if the outer diameter of the drum is only little smaller, e.g. by 2 to 5 percent, than the inner diameter of the casing, and if the drum rolls along the inner wall of the casing with a small minimum clearance, for example one of 0.04 inch. At least, the outer diameter of the drum should preferably exceed three quarters of ythe inner diameter of the casing. This is desirable not only for maintaining this cross-section between the heat transfer surfaces of the peripheral portions of the casing and of the housing, but also for maintaining these surfaces approximately equal. On the other hand, embodiments would be feasible in which the outer diameter of the drum is as low as 1A to 3A of the inner diameter of the casing. It must be borne in mind, however, that with small absolute values of the drum diameter there is the risk that the medium to be treated is no longer squeezed through the narrow gap between the drum and the casing but is displaced by the drum in front of it. As a result of the cross-section of the heat exchange space being strongly narrowed at one place only, while it is relatively wide elsewhere, comparatively small pressures suffice for circulating the medium through the heat exchanger.

In the described embodiment, the axes of the casing and of the drum are vertical; however, the two elements could also be arranged with their axes horizontal, without any change to the mode of operation of the heat exchanger.

We claim:

1. A heat exchanger comprising a cylindrical casing, shaft means rotatably supported in said casing for rotation about the axis thereof, a cylindrical drum closed at least at one of its ends located within said casing rotatably supported on said shaft means with its central axis parallel to the axis of rotation of said shaft means and spaced therefrom, said casing and drum having between them a space of substantially crescent-shaped cross-section for the fluid to be treated by heat exchange, said space having an inlet and an outlet QI said fluid, at

least one of said casing and drum having a double cylindrical wall providing duct means for the circulation of another fluid for exchanging heat with said first fluid.

2. A heat exchanger as claimed in claim 1 in which the external diameter of said drum exceeds one quarter of the internal diameter of said casing and said space between said drum and casing has a greatest radial width at least several times its smallest radial width.

3. A heat exchanger comprising a frame, a cylindrical casing supported endwise by said frame, an end cover fixed to said casing at its end remote from said frame, bearing means insaid frame and said cover in axial alignment with each other and with said casing, a lirst eccentric shaft rotatably supported in said frame bearing means, a second eccentric shaft rotatably supported in said cover bearing means, aneccentric trunnion on each of said first and second eccentric shafts in axial alignment with each other but radially olfset from the axis of mutual alignment of said bearing means, and a cylindrical drum rotatably supported on said aligned trunnions, said cylindrical drum having an outer diameter exceeding one quarter of the inner diameter of said casing and the radial clearance between said drum and casing on the side of the drum where said clearance is largest being at least equal to several times the same clearance on the diametrally opposite side of the drum, where vsuch clearance is smallest.

4. A heat exchanger as claimed in claim 3, wherein said frame bearing means comprises a sleeve of synthetic material, said first eccentric shaft comprises a second trunnion rotatably supported in said sleeve and a collar separating said second trunnion from said first trunnion, and another sleeve of synthetic material surrounding said lirst trunnion, and a spacing ring of synthetic material interposed between said casing and drum and surrounding said iirst eccentric shaft at said collar.

S. A heat exchanger as claimed in claim 3 wherein said casing and said drum have terminal walls spaced from and facing each other, said terminal wall of said casing having an inlet for the fluid to be treated by heat exchange, and said terminal wall of said drum having radial ribs for displacing said fluid towards the peripheral interval between said casing and drum.

6. A heat exchanger as claimed in claim 3 wherein the cylindrical peripheral portion of at least one of said casing and drum is double-walled and contains a helical duct for the circulation of another uid for exchanging heat with said first fluid.

References Cited by the Examiner UNITED STATES PATENTS 422,260 2/1890 Stephens 165-92 1,494,784 5/1924 Harley 308-174 1,554,299 9/1925 Seibel 308-139 1,701,777 2/1929 Jensen 165-92 X 1,930,808 10/1933 Hulbert 165-92 X 2,503,971 4/1950 Schneider 308-139 FOREIGN PATENTS 23,163 1895 Great Britain.

FREDERICK L. MATTESON, JR., Primary Examiner.

SUKALO, Examiner, 

1. A HEAT EXCHANGER COMPRISING A CYLINDRICAL CASING, SHAFT MEANS ROTATABLY SUPPORTED IN SAID CASING FOR ROTATION ABOUT THE AXIS THEREOF, A CYLINDRICAL DRUM CLOSED AT LEAST AT ONE OF ITS ENDS LOCATED WITHIN SAID CASING ROTATABLY SUPPORTED ON SAID SHAFT MEANS WITH ITS CENTRAL AXIS PARALLEL TO THE AXIS OF ROTATION OF SAID SHAFT MEANS AND SPACED THEREFROM, SAID CASING AND DRUM HAVING BETWEEN THEM A SPACE OF SUBSTANTIALLY CRESCENT-SHAPED CROSS-SECTION FOR THE FLUID TO BE TREATED BY HEAT EXCHANGE, SAID SPACE HAVING AN INLET AND AN OUTLET FOR SAID FLUID, AT LEAST ONE OF SAID CASING AND DRUM HAVING A DOUBLE CYLINDDRICAL WALL PROVIDING DUCT MEANS FOR THE CIRCULATION OF ANOTHER FLUID FOR EXCHANGING HEAT WITH SAID FIRST FLUID. 